93L near tropical depression strength

The first tropical depression of the 2010 Atlantic hurricane season appears imminent in the Western Caribbean, as the areal coverage and intensity of heavy thunderstorm activity associated with the tropical wave (Invest 93L) continue to increase. The storm has developed a surface circulation near 16.5N, 82.5W at 8am EDT, about 100 miles northeast of the Nicaragua/Honduras border. This is far enough from land that development will be slowed only slightly. Satellite loops show a poorly organized system, with only a modest amount of heavy thunderstorm activity near the center. However, the developing storm is affecting the weather across the entire Western Caribbean, and bands of heavy thunderstorms are quickly building over a large region. Pressures at ground stations and buoys all across the Western Caribbean have been falling significantly over the past day (Figure 2.) Water vapor satellite loops show that moist air surrounds 93L, and there is not much dry air to slow down development. There is an upper-level high pressure system a few hundred miles west of 93L, and the clockwise flow air around this high is bringing upper-level winds out of the northwest of about 10 - 15 knots over 93L, contributing to the 10 - 15 knots of wind shear observed in this morning's wind shear analysis from the University of Wisconsin's CIMSS group. Sea Surface Temperatures are very warm, 29 - 30°C. The Madden-Julian oscillation (MJO) currently favors upward motion over the Caribbean, which will act to increase the chances of tropical storm formation this week. The main negative for 93L is a combination of lack of spin and wind shear. Last night's pass of the ASCAT satellite showed a broad, elongated circulation, which will need to tighten up in order for 93L to become a tropical depression. The Hurricane Hunters are scheduled to fly into 93L at 2pm EDT this afternoon to see if a tropical depression has formed.

Figure 2. Combined plot of wind speed, wind gusts, and pressure at buoy 42057 in the Western Caribbean. Pressure (green line) has fallen significantly over the past two days, and winds are beginning to increase.

Forecast for 93LThe greatest risk from 93L to the Western Caribbean will be heavy rainfall, and the nation most at risk is Honduras. The counter-clockwise flow of air around 93L will bring bands of rain capable of bringing 4 - 8 inches of rain to northern Honduras over the next two days. Heavy rains of 3 - 6 inches can also be expected in northeast Nicaragua, Cuba, Belize, the Cayman Islands, and Mexico's Yucatan Peninsula. The storm is moving west-northwest at about 10 mph, and this motion is expected to gradually slow over the next five days to about 6 mph. I expect that by tomorrow, 93L should be closer to being directly underneath the upper level high pressure system to its west, which would act to lower wind shear and provide more favorable upper-level outflow. NHC is giving 93L a 70% chance of developing into a tropical depression by Sunday morning, which is a reasonable forecast. The storm will probably be a tropical depression or tropical storm with 40 mph winds when it moves over Mexico's Yucatan Peninsula on Sunday. The storm will probably spend a day or so over the Yucatan, resulting in significant weakening. Once 93L emerges over the Gulf of Mexico, it will take the storm 24+ hours to recover its strength.

A trough of low pressure is expected to swing down over the Eastern U.S. on Monday. If this trough is strong enough and 93L develops significantly, the storm could get pulled northwards and make landfall along the northern Gulf of Mexico coast. This is the solution of the GFDL and HWRF models. If 93L stays weak and/or the trough is not so strong, the storm would get pushed west-northwestwards across Mexico's Bay of Campeche and make landfall along Mexican coast south of Texas, or in Texas. This is the solution of the NOGAPS, ECMWF, and Canadian models. A likely landfall location is difficult to speculate on at this point, and the storm could hit virtually anywhere along the Gulf of Mexico coast given the current uncertainty in its development. The amount of wind shear in the Gulf of Mexico next week is also highly uncertain. There is currently a band of high shear near 30 knots over the Gulf. The GFS model predicts that this band of high shear will lift northwards, keeping low wind shear over the Gulf next week. However, the ECMWF model keeps high shear entrenched over the Gulf of Mexico, which would make it unlikely 93L could intensify into a hurricane. In summary, I give 93L a 60% chance of eventually becoming Tropical Storm Alex, and 10% chance of eventually becoming a hurricane.

Elsewhere in the tropicsA tropical wave a few hundred miles northeast of the northernmost Lesser Antilles Islands is producing a modest amount of heavy thunderstorm activity. This system was designated Invest 94 by NHC this morning, and is passing beneath a trough of low pressure that is generating 30 - 40 knots of wind shear. However, by Sunday, the storm will be in a region of much lower wind shear, and NHC is giving the storm a 10% chance of developing into a tropical depression by Sunday morning. We do have one model, the GFS, which develops the system early next week. The GFS model takes the storm to the northwest and then north, predicting it will be very close to Bermuda on Tuesday.

Impressive Hurricane Celia hits Category 5The first Category 5 hurricane in the Northern Hemisphere this year is Hurricane Celia in the Eastern Pacific. Celia's 160 mph winds make it tied with Australia's Tropical Cyclone Ului as the strongest tropical cyclone in the world so far in 2010. Celia has likely peaked in intensity, and is not expected to threaten any land areas.

Wind and ocean current forecast for the BP oil disasterEast to southeast winds of 5 - 15 knots will blow in the northern Gulf of Mexico today through Tuesday, according to the latest marine forecast from NOAA. The resulting weak ocean currents should push the oil to the west and northwest onto portions of the Louisiana and Alabama coasts, according to the latest trajectory forecasts from NOAA and the State of Louisiana. I would expect Mississippi to have its most serious threat of oil yet early next week as these winds continue. The longer range outlook is uncertain, and will depend upon what 93L does.

The only problem I have is the quoted NW movement. Do they think we are blind? All the relocation stuff does not mean NW. Storms move with the flow, tell me how that is NW? Its plain wrong to quote NW. When it goes S of Cozumel they still will not correct this error tell us how they were right. Goes to show how even experts can and are sometimes wrong. They post WNW track but quote NW movement. Guess it is supposed to move W later when conditions make it go more west when stronger. I just hate this kind of thing.

Wow, the MAIN storm area is now 10 deg wide. The storm just keeps converging and expanding into its own feeder bands.

Quoting taco2me61:Well with all due respect, If this storm hits the Texas coast it will bring Oil not only to LA but MS, AL and FL will get the Oilly Mess.... Because of the counter clock wise movement the waves from the east side of the storm move north. So all the oil just to the south of FL,AL and MS will move north....

Taco :o(

I'd hate to think how the toxic sludge will affect the wetlands and some of the whitest beaches in the world. If the oil becomes concentrated this could heat up the northeastern Gulf further.

Quoting HaboobsRsweet:The news story I saw said BP would have to if the storm became a threat...not that they were shutting down. They did say the cap would come off and takes 5 days to move everything out.

Yes... and it takes 5-days to move everything back. During that 10-day period, the pipe will keep discharging 700,000+ gallons/day of oil into the gulf.

I actually think BP can move out within a 3-day window if needed. The problem they will have is that this is an active season. They will have to mob-demob several times during the summer. This is going to get old really fast. If there is enough of a wave train coming through the Caribbean into the Gulf... they could even just suspend operations for a month or so.

The oil spill disaster is getting ready to move up to a new level of BAD!

Quoting RecordSeason:Based on the last several frames of infrared, along with Dr. Master's blog update and simply the sheer size of this storm combined with it's angle of motion, I have a feeling we are going to hear some terrible reports of flooding in central America.

This is by far some of the most powerful convection I've ever seen in anything that wasn't at least a hurricane.

I know they have mentioned the DR today... imagine for a second, this storm over Haiti, pounding away. All those areas down there really suffer with each tropical system that threatens (whether full force or just fringe effects).

If I am not mistaken, someone correct me if I am wrong about the models... but the early models are the statistical models (BAM, LBAR, etc.). The later models are the skilled models (GFS, ECM, etc.). The early models are first to "publish" so to speak. To put it simply, anyways.

Forecast models are characterized as either early or late, depending on whether they are available to the forecaster during the forecast cycle. For example, consider the 1200 UTC forecast cycle, which begins with the 1200 UTC synoptic time and ends with the release of an official forecast at 1500 UTC. The 1200 UTC run of the NWS/Global Forecast System (GFS) model is not complete and available to the forecaster until about 1600 UTC, an hour after the forecast is released. Thus, the 1200 UTC GFS would be considered a "late" model since it could not be used to prepare the 1200 UTC official forecast. Conversely, the BAM models are generally available within a few minutes of the time they are initialized. Therefore, they are termed "early" models. Model timeliness is listed in Table 1.

Due to their complexity, dynamical models are generally, if not always, late models. Fortunately, a technique exists to take the latest available run of a late model and adjust its forecast so that it applies to the current synoptic time and initial conditions. In the example above, forecast data for hours 6-126 from the previous (0600 UTC) run of the GFS would be smoothed and then adjusted, or shifted, so that the 6-h forecast (valid at 1200 UTC) would match the observed 1200 UTC position and intensity of the TC. The adjustment process creates an "early" version of the GFS model that becomes part of the most current available guidance for the 1200 UTC forecast cycle. The adjusted versions of the late models are known, largely for historical reasons, as "interpolated" models.

Yeah kinda a lull in the action. I guess people are just watching and waiting right noww for the 11pm update. Then the blog will light up as usual with the "I told you so's"... "See I told you it was coming to (this state)" LOL!

The reason I said this is because I had a hurricane Hunter talk to my school about flying into hurricanes, and he said it was definately a lot scarier to fly into a depression/disturbance/storm than into a hurricane. He told us horror stories about flying into a depression one time. He also mentioned that flying into a hurricane was really easy. When I heard this, i was surprised as well. Really interesting!

The uniform flow around a hurricane makes it much more calm in regards to turb while depressions are so scattered you see rapid change in speed and direction since it is so disorganized meaning more turb.

Quoting sailingallover:not over the water, not much anyway..this being based on being in boats in ones.on land near any kind of hills and even in the ICW in florida the turbulence can be bad.. on the hilly islands of the caribbean it can be DEVASTATING.

yes because he hills and mountains cause a change in direction just like mountain wave turb. This also changes the speed. Forces the air up and gives you a tigher gradiant increasing speed near the mountain.

Quoting MiamiHurricanes09:True but a gust of 150 miles an hour causes more turbulence than a gust of 50 miles per hour.

It is the delta that you have to worry about aka the change. If the gust spread is 25kts sustained to 50kts then you will have more than in a hurricane of 140kts gusting 150kts. This is why Tstorms are a major no no to fly in. You can fly in hurricanes.

Quoting HaboobsRsweet:I do not htink that is 100% true. A hurricane actually does not have a lot of turblance because it is uniform and the speed is similar around the same path. To have turblence you need rapid change in speed or direction and that doesnt really happen much in a hurricane.

not over the water, not much anyway..this being based on being in boats in ones.on land near any kind of hills and even in the ICW in florida the turbulence can be bad.. on the hilly islands of the caribbean it can be DEVASTATING.

IKE, in a sense I am kinda surprised too... However, it may be because of the strongest winds are located north of the center. There would be no need for a Tropical Storm Warning in that case. Though I bet they may be getting Tropical Storm force wind gusts in squalls.

Quoting MiamiHurricanes09:True, but when in a hurricane you are experiencing much stronger turbulence than in a tropical depression, per se. Yes it is calm when you are in the eye, but what if it is needed to analyze the eye wall?

The reason I said this is because I had a hurricane Hunter talk to my school about flying into hurricanes, and he said it was definately a lot scarier to fly into a depression/disturbance/storm than into a hurricane. He told us horror stories about flying into a depression one time. He also mentioned that flying into a hurricane was really easy. When I heard this, i was surprised as well. Really interesting!